Product having calcified egg shell particles having diameter of 3 microns or less

ABSTRACT

Disclosed herein are systems and methods for processing waste egg shells into (i) a first product including calcified egg shell particles having diameters of 3μ or less, and (ii) a second product including calcified egg shell particles having diameters in a range from about 3μ to about 7μ. The first product may be used as a CaCO 3  substitute for paint compositions and plastics compositions. The second product may be used as a CaCO 3  blasting media substitute for use with abrasive blasting equipment.

TECHNICAL FIELD

This disclosure generally relates to processing of waste egg shells.More specifically, this disclosure pertains to systems and methods forseparating membranes from egg shells and then processing de-membranizedegg shells into fractions suitable for use as CaCO₃ filler substitutesfor paints, resins, topical compositions, and for use as abrasiveblasting media.

BACKGROUND

The increasing volumes of eggs used for large-scale commercialproduction of egg-based fast foods and food products, baking and cookingingredients, and the like is resulting in large accumulations of wasteegg shells. There have been many attempts to derive products from wasteegg shells and some small-scale commercial activities have resulted inseparation of the inner membranes from the outer calcified shellcomponents of egg shells. Separated and purified egg shell membraneshave been incorporated into oral supplements and topical lotions andcreams based on the high levels of collagen and other useful proteins inthe membranes. The calcified outer egg shell components are typicallyground into coarse and fine granules that are most commonly incorporatedinto poultry and animal feeds and feed supplements. Alternatively,ground calcified outer egg shell components can be used as soilagronomic supplements and amendments.

Although useful products can be derived from processing waste eggshells, the problem is that the prices consumers are willing to pay forproducts comprising ground calcified egg shell granules are notsufficiently high enough to cover the costs of processing and producingthese types of products. Consequently, the vast majority of commerciallyproduced waste egg shells is simply disposed of in garbage dumps andlandfill sites.

SUMMARY

The embodiments of the present disclosure generally relate to systemsand methods for processing waste egg shells into commercially usefulproducts.

One embodiment of the present disclosure pertains to systems comprisinga plurality of equipment configured for cooperatively receiving wasteegg shells, washing the waste egg shells, separating the membranecomponents from the calcified solids components of the egg shells,washing the de-membranized calcified solids components, drying thede-membranized calcified solids components, milling the dried calcifiedsolids components, separating out three fractions of milled calcifiedsolids components wherein the first fraction comprises calcifiedparticles having a diameter of three microns or less, the secondfraction comprises calcified particles having diameters from the rangeof about three microns to seven microns, and the third fractioncomprises calcified particles having diameters greater than sevenmicrons, re-milling the third fraction and separating out the first andsecond fractions until no more of the third fraction remains, andseparately collecting the first fraction and the second fraction. Anaspect of this embodiment pertains to separately collecting the membranecomponents after the separation of the membrane components from eggshell calcified solids components.

An embodiment of the present disclosure pertains to methods forprocessing waste eggs shells to separate out and collect: (i) a firstproduct comprising calcified solids particles having a diameter of threemicrons or less, and (ii) a second product comprising calcifiedparticles having diameters from the range of about three microns toseven microns. An aspect of this embodiment pertains to methods thatadditionally comprise collection of a third product comprising membranecomponents separated from waste egg shells.

Another embodiment of the present disclosure pertains to packaging ofthe first egg shell calcified solids particle product for use as afiller in resinous polymer compositions such as epoxy resins, vinylesterresins, polyester resins, and the like. The first egg shell calcifiedsolids particle product may also be packaged for use as a filler inpaint compositions such as latex paints, alkyd paints, and the like. Anaspect of this embodiment pertains to resinous polymer compositionscomprising the first egg shell calcified solids particle product.Another aspect of this embodiment pertains to paint compositionscomprising the first egg shell calcified particle solids product.

Another embodiment of the present disclosure pertains to packaging ofthe second egg shell calcified solids particle product for use as ablasting media with abrasive blasting equipment for cleaning and removalof surface coverings from underlying solid surfaces and articles.

Another embodiment of the present disclosure pertains to packaging ofthe third product comprising the egg shell membrane components, forfurther processing to produce collagen-based products therefrom.

BRIEF DESCRIPTION OF THE FIGURES

The embodiments of the present disclosure will be described withreference to the following drawings in which:

FIG. 1 is a schematic diagram illustrating an example of a waste eggshell processing system according to one embodiment of the presentdisclosure;

FIG. 2 is an optical coherence tomography (OCT) image of a side view ofa section of uncoated concrete;

FIG. 3 is an OCT image of a side view of a section of concrete coatedwith a commercial primer composition;

FIG. 4 is an OCT image of a side view of a section of concrete having afirst coating with a commercial primer composition which was overlaidwith a second coating containing calcium carbonate powder;

FIG. 5 is an OCT image of a side view of a section of concrete whereinthe right side of the section was uncoated and the left side of thesection received a first coating with a commercial primer compositionwhich was overlaid with a second coating containing calcium carbonatepowder;

FIG. 6 is an OCT image of a side view of a section of concrete having afirst coating with a commercial primer composition which was overlaidwith a second coating containing egg shell calcified particles producedwith a method disclosed herein; and

FIG. 7 is an OCT image of a side view of a section of concrete whereinthe right side of the section was uncoated and the left side of thesection received a first coating with a commercial primer compositionwhich was overlaid with a second coating containing egg shell calcifiedparticles produced with a method disclosed herein.

DETAILED DESCRIPTION

We have surprisingly discovered that egg shells from which the membranescomponents have been removed, can be milled to produce twovery-fine-powdered fractions referred to herein as egg shell calcifiedparticles, that can be used to substitute for chemically synthesized orchemically derived calcium carbonate (CaCO₃) and for pulverized quarriedor mined limestone in various industrial applications. The firstfraction i.e., product, comprises egg shell calcified particles having aparticle size of 3μ or less, while the second fraction i.e., product,comprises egg shell calcified particles having particle sizes from arange of about 3μ to 7μ.

Consumers are becoming increasingly desirous of products that havereduced contents of chemically synthesized or chemically derivedconstituents. Industrial manufacturers of, for example, constituents forincorporation into paint compositions and plastics compositions, aretrying to satisfy such consumer interest by substituting for thechemically synthesized or chemically derived constituents with suitablenaturally occurring components or with physically modified naturallyoccurring components (i.e., not by chemical processing). Additionally,manufacturers of such products are looking for ingredients by which theycan reduce their carbon footprint, for example, by using ingredientswith reduced requirements for processing thereby requiring less energy,and/or which do not originate from chemical synthesis manufacturingprocesses.

Most of the CaCO₃ used in industry is extracted from mined or quarriedlimestone which is then crushed and sieved to provide crushed limestonegrains having selected ranges of mesh sizes. However, limestone containsother mineral and organic components which tend to make crushedlimestone unsuitable for incorporation into paint and plasticscompositions. These industries use precipitated CaCO₃ that is producedfrom calcium oxide dispersed in water through which is then passedcarbon dioxide to precipitate out CaCO₃. There is a growing segment ofpaint formulators and manufacturers that are replacing some of theprecipitated CaCO₃ with clays and/or talcs and are referring to theirpaints as “ecopaints” of “biopaints”. Plastics manufacturers have longused plant-derived materials such as starch, cellulose and proteins toreplace some or all of the petroleum-based polymers in theirformulations, and commonly refer to such plastics as bioplastics orecoplastics. However, precipitated CaCO₃ is commonly used as a filler inplastics comprising plant-derived polymers.

We have discovered that egg shell calcified particles having a particlesize of 3μ or less produced by the methods disclosed herein, can be usedas a replacement for precipitated CaCO₃ and clays and talcs in paintcompositions. We have also discovered that egg shell calcified particleshaving a particle size of 3μ or less produced by the methods disclosedherein, can be used as a replacement for precipitated CaCO₃ as a fillerfor formulating plastics compositions. Furthermore, such egg shellcalcified particles can be substituted as fillers for precipitated CaCO₃in any other application wherein precipitated CaCO₃ is used, for examplesealers, glues, and the like.

Crushed CaCO₃ produced from quarried or mined limestone is commonly usedas a blasting media for gentle abrasive cleaning and stripping ofcoverings on solid surfaces and substrates wherein the coverings are oneor more of paint, varnish, rust, grime, soot, oil films, spray-paintedgraffiti, and the like. The particle i.e., grain sizes of commerciallyavailable crushed CaCO₃ blasting media are typically in the range of 70mesh (210μ) to 130 mesh (115μ) with a hardness rating of 2-3 Mohsmedium. We have found that egg shell calcified particles from a range ofabout 3μ to 7μ are well-suited for use with abrasive blasting equipmentas a substitute for crushed CaCO₃ blasting media and that the smalleregg shell calcified particle size (i.e., 3μ to 7μ) provides a softeri.e., more gentle cleaning and stripping function when used withabrasive blasting equipment. Furthermore, such egg shell calcifiedparticles can be substituted as fillers for crushed CaCO₃ in any otherapplication wherein crushed CaCO₃ is used, for example paints,composites, sealers, glues, and the like.

Accordingly, one embodiment of the present disclosure pertains to amethod for processing waste egg shells to produce therefrom two eggshell calcified particle products wherein one product comprises eggshell calcified particles having a diameter of 3μ (˜4000 mesh) or less,and is suitable for use as a CaCO₃ substitute in paint compositions,plastics compositions, topical cosmetics compositions, and dentalfilling compositions, and the second product comprises egg shellcalcified particles having diameters from a range of about 3μ (˜4000mesh) to 7μ (˜1900 mesh) and is suitable for use as a blasting mediawith abrasive blasting equipment.

The methods according to this disclosure generally comprise the stepsof:

-   1. separating the membrane components of waste egg shells from the    calcified outer shell components to produce de-membranized egg shell    calcified components.    -   It is optional if so desired, to provide a pre-processing waste        egg shell washing step to remove any egg yolk and/or egg white        residues that may be present on the inner-facing surfaces of the        egg shells.-   2. washing the de-membranized egg shell calcified components to    remove any remaining membrane components, then drying the washed    de-membranized egg shell calcified components.-   3. milling the dried de-membranized egg shell calcified components    to produce small-diameter particles therefrom.-   4. separating the milled small-diameter egg shell calcified    particles into three fractions wherein the first fraction comprises    particles having diameters of 3μ or less, the second fraction    comprises particles having diameters in a range from about 3μ to    about 7μ, and the third fraction comprises particles having    diameters greater than 7μ.-   5. re-milling the third fraction and then separating additional    quantities of the first fraction the second fraction, and if    necessary, the third fraction.-   6. repeating step 5 as many times as necessary to eliminate egg    shell calcified particles with diameters greater than 7μ.-   7. separately packaging the first fraction i.e. the first product    and the second fraction i.e. the second product.    -   Suitable packaging may include:    -   paper bags, for example the bags may be sized to sealably        contain 0.5 lb, 1 lb, 2 lb, 2.5 lb, 3 lb, 4 lb, 5 lb, 10 lb, 25        lb, 50 lb, 100 lb, and therebetween,    -   bottles, for example the bottles may be sized to contain 50 g,        100 g, 250 g, 500 g, 1 kg, 5 kg, and therebetween,    -   pails, for example the pails may be sized to contain 10 lb, 25        lb, 50 lb, and therebetween,    -   drums, for example the drums may be sized to contain 25 lb, 50        lb, 75 lb, 100 lb, 200 lbs, and therebetween,    -   bulk bags, for example the bulk bags may be sized to contain ¼        tonne, ½ tonne, ¾ tonne, 1 tonne, and therebetween,    -   However, it is within the scope of this disclosure to use any        suitable packaging for separately containing therein the first        product or the second product.

The present methods optionally comprise one or more additional steps ofcollecting and packaging the membrane components separated in step 1,for use in other types of applications.

Another embodiment of the present disclosure pertains to systemscomprising a plurality of equipment configured for cooperativelyprocessing waste egg shells into a first product comprising egg shellcalcified particles having diameters of 3μ or less, a second productcomprising egg shell calcified particles having diameters in a rangefrom about 3μ to about 7μ and optionally, a third product comprisingmembrane components separated from waste egg shells.

It is to be noted that the methods may be batch methods wherein aselected batch size of waste egg shells is prepared and then processedto output the first product, the second product, and optionally, thethird product. Alternatively, the methods may be continuous methodswherein a constant supply of waste egg shells is delivered to the firststep of the method and constant outputs of the first product, the secondproduct, and optionally the third product are collected and packaged.Alternatively, the methods may be semi-continuous methods wherein aconstant supply of waste egg shells is delivered to the first step ofthe method for an extended period of time for example 2 h, 3, 4, 6, 8,12, 18, and therebetween, during which time constant outputs of thefirst product, the second product, and optionally the third product arecollected and packaged.

An example of a system 10 according to the present disclosure isillustrated in FIG. 1, and generally comprises five primary components.

The first primary component 20 is equipment for separating membranesfrom waste egg shells. Such equipment is known and publically disclosed,for example, in U.S. Pat. Nos. 8,418,943, 8,448,884, 9,370,778 amongothers. It is optional, if so desired, provide a suitable industrialwashing machine 15 to remove residual egg yolk and/or egg white from theinner surfaces of the waste egg shells prior to transfer of the wasteegg shells into the membrane separation equipment.

The second primary component is a suitable industrial washing machine 30to separate any residual membrane from the egg shells that was notcompletely removed by the membrane separation equipment 20. This washingmachine 30 may be the same as the first washing machine 15 or not.

The third primary component is a suitable industrial drier 40 for dryingtherein the wash de-membranized egg shells. It is within the scope ofthe present invention to incorporate into the system 10 any of a traydrier, a tumble drier, a centrifugal dewatering machine, an air jetdrier, and the like.

The fourth primary component is a suitable milling machine 50 forpowderizing the egg shell fragments into very fine particulates.

The fifth primary component is a powder separator 60 to separate out anddeliver the first fraction into a collection container 70 for receivingproduct 1 comprising egg shell calcified particles having diameters of3μ or less, to separate out and deliver the second fraction into acollection container 80 for receiving product 2 comprising egg shellcalcified particles having diameters in a range from about 3μ to about7μ, and to separate the third fraction 90 comprising egg shell calcifiedparticles having diameters larger than about 7μ into a conveyanceequipment for delivery of the third fraction 90 back into the millingmachine 50 for further milling and powderizing.

It is optional if so desired, to configure the membrane/shell separatingequipment 20 to concentrate the separated membrane components anddeliver the concentrated membrane components to a suitable productcontainer 95.

It is to be noted that the systems disclosed herein may be configured asbatch throughput systems wherein a selected batch size of waste eggshells is received and processed to output the first product, the secondproduct, and optionally, the third product. Alternatively, the systemsmay be continuous throughput systems wherein a constant supply of wasteegg shells is delivered to the first components and processed constantlyto output the first product, the second product, and optionally thethird product. Alternatively, the systems may be semi-continuousthroughput systems wherein a constant supply of waste egg shells isdelivered to the first components of the systems for an extended periodof time, for example 2 h, 3, 4, 6, 8, 12, 18, and therebetween, duringwhich time constant outputs of the first product, the second product,and optionally the third product are processed.

Another embodiment of the present disclosure pertains to an egg shellcalcified particle product for use as a filler in coating compositionssuch as paints, sealers, and the like, wherein the egg shell calcifiedparticles have diameters of 3μ or less, and wherein the egg shellcalcified particle product is produced from waste egg shells using thesystem and/or methods disclosed herein.

Another embodiment of the present disclosure pertains to an egg shellcalcified particle product for use as a filler in cosmetics topicalcompositions such as moisturizers, lotions, creams, facial scrubs, andthe like, wherein the egg shell calcified particles have diameters of 3μor less, and wherein the egg shell calcified particle product isproduced from waste egg shells using the system and/or methods disclosedherein.

Another embodiment of the present disclosure pertains to an egg shellcalcified particle product for use as a filler dental fillingcompositions, wherein the egg shell calcified particles have diametersof 3μ or less, and wherein the egg shell calcified particle product isproduced from waste egg shells using the system and/or methods disclosedherein.

Another embodiment of the present disclosure pertains to an egg shellcalcified particle product for use as an abrasive blasting media withabrasive blasting equipment compositions, wherein the egg shellcalcified particles having diameters in a range from about 3μ to about7μ, and wherein the egg shell calcified particle product is producedfrom waste egg shells using the system and/or methods disclosed herein.

EXAMPLE

The purpose of this study was to compare the performance of a waste eggshell calcified particle product as a calcium carbonate substitute insealers used for coating concrete.

Waste egg shells were processed by the following method to produce asample egg shell calcified particle product.

-   1. The membrane components of the waste egg shells were separated    from the calcified outer shell components to produce de-membranized    egg shell calcified components.-   2. The de-membranized egg shell calcified components were washed to    remove any remaining membrane components, and then were dried.-   3. The dried de-membranized egg shell calcified components were    milled in a laboratory-scale hammer mill to produce a powdered    product comprising small-diameter egg shell calcified particles.-   4. The powdered small-diameter egg shell calcified particles sieved    to separate a fraction of particles having diameters of 3μ or less    from the larger particles.-   5. The milling and sieving steps were repeated until most of the    milled egg shell calcified particles had diameters of 3μ or less.

Cement paving blocks having dimensions 12″×12″×1.5″ (L, W, D) receivedone of the following coatings on their top surfaces: (i) coated with acommercial primer coating, (ii) coated with a commercial primer coatingwhich was then overlaid with a coating mixture comprising calciumcarbonate, (iii) coated with a commercial primer coating which was thenoverlaid with a coating mixture comprising the milled egg shellcalcified particles, and (iv) no coating (control). Some of the concretepaving blocks were divided into two equal sections wherein one sectionwas untreated and the other section was coated with a commercial primercoating which was then overlaid with a coating mixture comprisingcalcium carbonate. Other concrete paving blocks were divided into twoequal sections wherein one section was untreated and the other sectionwas coated with a commercial primer coating which was then overlaid witha coating mixture comprising the milled egg shell calcified particles.

The surfaces of the cement paving blocks were examined with opticalcoherence tomography (OCT) using a surface-scanning probe headcomprising a light source focused through a lens having a 5-mm focaldistance. The light back-scattered by the sample propagates back throughthe lens and toward the detection of the OCT system. The detected signalincoming from one single location of the focused probing beam wasrecorded and represents one depth scan. A full OCT image was obtained byscanning the lens from one point to the next, each time recording adepth scan corresponding to that specific location. Each OCT imageacquired for this study (FIGS. 2-7) contained 6,000 depth scans, withthe distance between two consecutive depth scans being 2.5 micrometers.The incoming probing beam approached the samples from the top in allcases.

In every OCT image from this study, the unit scale along the horizontalaxis was 2.5 micrometers per pixel, and the unit scale along thevertical axis (depth axis) was 1.0 micrometers per pixel. Multiple OCTimages were acquired from all samples in order to establish a pattern ofconsistency for each sample.

FIG. 2 shows an OCT image of the uncoated side of a concrete pavingblock. Details such as surface imperfections (pores) and empty pockets(voids) located under the concrete surface are clearly distinguishable.

FIG. 3 shows an OCT image of the primer layer applied over the poroussurface of a concrete paving block. The intensity bar shown on the righthas red corresponding to the strongest OCT signal and dark blue to theweakest signal recorded in the image. The air/primer interface is markedas “Surface”. Clearly visible in FIG. 3 is how the primer filled theconcrete pores and voids with two examples of filled voids encircled.The interfaces that mark the boundaries between the primer and concreteare also visible. A very good example of primer/concrete separation ismarked to the right of FIG. 3 and shows one big void filled with primerwhose volume is also split in two by a concrete peak. The primerthoroughly filled all the surface pores. Important to note in FIG. 3 isthat the signal acquired from within the primer pockets which fill theconcrete pores does not have a “spotty” (i.e. speckled) appearance, likethe spotty appearance displayed by the signal acquired from within theconcrete. This means that the primer is not only transparent but alsodoes not scatter the probing light and this is how primer isdifferentiated from coating material in the OCT images.

FIG. 4 shows the surface of a concrete paving block that received acalcium carbonate coating applied over the primer layer. “The firstinterface” (the air/coating interface) is obvious in the image. Theimage also shows clear differences between porous regions filled withcalcium carbonate and the surrounding concrete matrix. For convenience,some of the pores filled with calcium carbonate are circled. It is notedthat the speckles (“spots”) of the signal acquired from regions withcalcium carbonate are finer and look denser that the signal “spots” fromregions with concrete. From the finer and dense speckle display we canconclude that the calcium carbonate particles distribute themselvesquite homogeneous within the primer layer. In addition, it is possibleto identify pools of primer which did not mix with calcium carbonate.Two such examples are circled. There are also “secondary interfaces”that can be distinguished within the calcium carbonate layer. One suchexample is also marked. Although of dim intensity, by looking carefullyacross this figure, other such secondary interfaces are also visible.

FIG. 5 shows an OCT image of a region located at the boundary betweenuncoated and calcium carbonate-coated concrete. Features such as the“secondary Interfaces” observed in FIG. 4, are also visible on thecoated side from FIG. 5. Pools of primer are also present at the bottomof some pores. Another detail in this image is the presence of a pieceof un-mixed primer just at the coated/uncoated boundary labeled as“primer not CaCO3”. This can be identified as primer due to the lack ofthe spotty pattern (i.e. speckle) which characterizes the OCT signalcoming from locations with calcium carbonate.

FIG. 6 shows an OCT image acquired from a region coated with egg shellcalcified particles/primer mix. There are some similarities with thecalcium carbonate coating shown in FIG. 5, for example the interfaceseparating the air from the coating, as well as the pools of primer fromthe bottom of some of the concrete surface pores. There are also someobvious differences between the two cases. Firstly, the particle densityof eggshell coating is not uniform. Based on speckle densities observedacross the eggshell layer, it can be can inferred that there arelocations with high density and low density of particles across thecoated region. It is also apparent that the adjacent regions withdifferent eggshell calcified particles concentrations are separated byinterfaces. There are two examples circled in FIG. 6, one marks ahigh-density region and the other marks a low-particle-density region.The low-density regions are located toward the surface of the coating,very near the air/coating interface and very often actually forms thatinterface. This indicates that the egg shell calcified particles diffusedeeper into the concrete pores, i.e. toward the bottom of the coatinglayer, during the time period before the layer solidifies.

FIG. 7 shows an OCT image of a region located at the boundary of aconcrete paving block between an uncoated surface and a surface coatedwith primer and egg shell calcified particles. The features observed andnoted in FIG. 6 are also visible on the coated side of this concretepaving block.

Based on the comparisons of OCT images of concrete paving blocks coatedwith a primer and calcium carbonate with OCT images of concrete pavingblocks coated with a primer and egg shell calcified particles, it isclear that calcium carbonate components of commercial sealers can besubstituted for with egg shell calcified particles produced as disclosedherein.

1. A product including calcified egg shell particles having diameters of3μ or less.